Mesh networks, contrary to ring networks, are those comprising a number of inter-linked star-like connections between NE (network elements). A connection between two adjacent NE is usually called a span.
To perform urgent path restorations and other reconfiguring actions in the network when failures occur, either NEs or any managing entity should be informed on the current condition of each span in the network, and in the minimal time.
Presently, this service action is usually provided by a so-called network management station (NMS) of the network, via service channels. The NMS has a network level view of the “network health status”. NMS receives notifications and alarms about failed links and re-calculates new trails in the network to bypass such links. The information/instructions with respect to the new corrected trails is then downloaded to the relevant network elements. The described process is known as a restoration process. In mesh networks, it takes a considerable time for execution due to complexity of configuration of such networks.
The OSPF protocol (Open Short Path First protocol) which is widely used in IP networks relates to the family of “link state protocols”. This protocol enables exchanging the routing information which has been updated due to the network topology changes (span addition/deletion, failure). It is a complex and highly software dependent protocol. A considerable portion of the time is required for updating NMS and each and every node in the network about the new status of the “network health”. Furthermore, the restoration cannot be accomplished if the NMS is down by any reason.